timing.c

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/*
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License, version 2, as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 *
 * Copyright IBM Corp. 2008
 *
 * Authors: Hollis Blanchard <[email protected]>
 *          Christian Ehrhardt <[email protected]>
 */

#include <linux/kvm_host.h>
#include <linux/fs.h>
#include <linux/seq_file.h>
#include <linux/debugfs.h>
#include <linux/uaccess.h>
#include <linux/module.h>

#include <asm/time.h>
#include <asm-generic/div64.h>

#include "timing.h"

void kvmppc_init_timing_stats(struct kvm_vcpu *vcpu)
{
    int i;

    /* Take a lock to avoid concurrent updates */
    mutex_lock(&vcpu->arch.exit_timing_lock);

    vcpu->arch.last_exit_type = 0xDEAD;
    for (i = 0; i < __NUMBER_OF_KVM_EXIT_TYPES; i++) {
        vcpu->arch.timing_count_type[i] = 0;
        vcpu->arch.timing_max_duration[i] = 0;
        vcpu->arch.timing_min_duration[i] = 0xFFFFFFFF;
        vcpu->arch.timing_sum_duration[i] = 0;
        vcpu->arch.timing_sum_quad_duration[i] = 0;
    }
    vcpu->arch.timing_last_exit = 0;
    vcpu->arch.timing_exit.tv64 = 0;
    vcpu->arch.timing_last_enter.tv64 = 0;

    mutex_unlock(&vcpu->arch.exit_timing_lock);
}

static void add_exit_timing(struct kvm_vcpu *vcpu, u64 duration, int type)
{
    u64 old;

    mutex_lock(&vcpu->arch.exit_timing_lock);

    vcpu->arch.timing_count_type[type]++;

    /* sum */
    old = vcpu->arch.timing_sum_duration[type];
    vcpu->arch.timing_sum_duration[type] += duration;
    if (unlikely(old > vcpu->arch.timing_sum_duration[type])) {
        printk(KERN_ERR"%s - wrap adding sum of durations"
            " old %lld new %lld type %d exit # of type %d\n",
            __func__, old, vcpu->arch.timing_sum_duration[type],
            type, vcpu->arch.timing_count_type[type]);
    }

    /* square sum */
    old = vcpu->arch.timing_sum_quad_duration[type];
    vcpu->arch.timing_sum_quad_duration[type] += (duration*duration);
    if (unlikely(old > vcpu->arch.timing_sum_quad_duration[type])) {
        printk(KERN_ERR"%s - wrap adding sum of squared durations"
            " old %lld new %lld type %d exit # of type %d\n",
            __func__, old,
            vcpu->arch.timing_sum_quad_duration[type],
            type, vcpu->arch.timing_count_type[type]);
    }

    /* set min/max */
    if (unlikely(duration < vcpu->arch.timing_min_duration[type]))
        vcpu->arch.timing_min_duration[type] = duration;
    if (unlikely(duration > vcpu->arch.timing_max_duration[type]))
        vcpu->arch.timing_max_duration[type] = duration;

    mutex_unlock(&vcpu->arch.exit_timing_lock);
}

void kvmppc_update_timing_stats(struct kvm_vcpu *vcpu)
{
    u64 exit = vcpu->arch.timing_last_exit;
    u64 enter = vcpu->arch.timing_last_enter.tv64;

    /* save exit time, used next exit when the reenter time is known */
    vcpu->arch.timing_last_exit = vcpu->arch.timing_exit.tv64;

    if (unlikely(vcpu->arch.last_exit_type == 0xDEAD || exit == 0))
        return; /* skip incomplete cycle (e.g. after reset) */

    /* update statistics for average and standard deviation */
    add_exit_timing(vcpu, (enter - exit), vcpu->arch.last_exit_type);
    /* enter -> timing_last_exit is time spent in guest - log this too */
    add_exit_timing(vcpu, (vcpu->arch.timing_last_exit - enter),
            TIMEINGUEST);
}

static const char *kvm_exit_names[__NUMBER_OF_KVM_EXIT_TYPES] = {
    [MMIO_EXITS] =              "MMIO",
    [DCR_EXITS] =               "DCR",
    [SIGNAL_EXITS] =            "SIGNAL",
    [ITLB_REAL_MISS_EXITS] =    "ITLBREAL",
    [ITLB_VIRT_MISS_EXITS] =    "ITLBVIRT",
    [DTLB_REAL_MISS_EXITS] =    "DTLBREAL",
    [DTLB_VIRT_MISS_EXITS] =    "DTLBVIRT",
    [SYSCALL_EXITS] =           "SYSCALL",
    [ISI_EXITS] =               "ISI",
    [DSI_EXITS] =               "DSI",
    [EMULATED_INST_EXITS] =     "EMULINST",
    [EMULATED_MTMSRWE_EXITS] =  "EMUL_WAIT",
    [EMULATED_WRTEE_EXITS] =    "EMUL_WRTEE",
    [EMULATED_MTSPR_EXITS] =    "EMUL_MTSPR",
    [EMULATED_MFSPR_EXITS] =    "EMUL_MFSPR",
    [EMULATED_MTMSR_EXITS] =    "EMUL_MTMSR",
    [EMULATED_MFMSR_EXITS] =    "EMUL_MFMSR",
    [EMULATED_TLBSX_EXITS] =    "EMUL_TLBSX",
    [EMULATED_TLBWE_EXITS] =    "EMUL_TLBWE",
    [EMULATED_RFI_EXITS] =      "EMUL_RFI",
    [DEC_EXITS] =               "DEC",
    [EXT_INTR_EXITS] =          "EXTINT",
    [HALT_WAKEUP] =             "HALT",
    [USR_PR_INST] =             "USR_PR_INST",
    [FP_UNAVAIL] =              "FP_UNAVAIL",
    [DEBUG_EXITS] =             "DEBUG",
    [TIMEINGUEST] =             "TIMEINGUEST"
};

static int kvmppc_exit_timing_show(struct seq_file *m, void *private)
{
    struct kvm_vcpu *vcpu = m->private;
    int i;
    u64 min, max, sum, sum_quad;

    seq_printf(m, "%s", "type   count   min max sum sum_squared\n");


    for (i = 0; i < __NUMBER_OF_KVM_EXIT_TYPES; i++) {

        min = vcpu->arch.timing_min_duration[i];
        do_div(min, tb_ticks_per_usec);
        max = vcpu->arch.timing_max_duration[i];
        do_div(max, tb_ticks_per_usec);
        sum = vcpu->arch.timing_sum_duration[i];
        do_div(sum, tb_ticks_per_usec);
        sum_quad = vcpu->arch.timing_sum_quad_duration[i];
        do_div(sum_quad, tb_ticks_per_usec);

        seq_printf(m, "%12s %10d    %10lld  %10lld  %20lld  %20lld\n",
            kvm_exit_names[i],
            vcpu->arch.timing_count_type[i],
            min,
            max,
            sum,
            sum_quad);

    }
    return 0;
}

/* Write 'c' to clear the timing statistics. */
static ssize_t kvmppc_exit_timing_write(struct file *file,
                       const char __user *user_buf,
                       size_t count, loff_t *ppos)
{
    int err = -EINVAL;
    char c;

    if (count > 1) {
        goto done;
    }

    if (get_user(c, user_buf)) {
        err = -EFAULT;
        goto done;
    }

    if (c == 'c') {
        struct seq_file *seqf = file->private_data;
        struct kvm_vcpu *vcpu = seqf->private;
        /* Write does not affect our buffers previously generated with
         * show. seq_file is locked here to prevent races of init with
         * a show call */
        mutex_lock(&seqf->lock);
        kvmppc_init_timing_stats(vcpu);
        mutex_unlock(&seqf->lock);
        err = count;
    }

done:
    return err;
}

static int kvmppc_exit_timing_open(struct inode *inode, struct file *file)
{
    return single_open(file, kvmppc_exit_timing_show, inode->i_private);
}

static const struct file_operations kvmppc_exit_timing_fops = {
    .owner   = THIS_MODULE,
    .open    = kvmppc_exit_timing_open,
    .read    = seq_read,
    .write   = kvmppc_exit_timing_write,
    .llseek  = seq_lseek,
    .release = single_release,
};

void kvmppc_create_vcpu_debugfs(struct kvm_vcpu *vcpu, unsigned int id)
{
    static char dbg_fname[50];
    struct dentry *debugfs_file;

    snprintf(dbg_fname, sizeof(dbg_fname), "vm%u_vcpu%u_timing",
         current->pid, id);
    debugfs_file = debugfs_create_file(dbg_fname, 0666,
                    kvm_debugfs_dir, vcpu,
                    &kvmppc_exit_timing_fops);

    if (!debugfs_file) {
        printk(KERN_ERR"%s: error creating debugfs file %s\n",
            __func__, dbg_fname);
        return;
    }

    vcpu->arch.debugfs_exit_timing = debugfs_file;
}

void kvmppc_remove_vcpu_debugfs(struct kvm_vcpu *vcpu)
{
    if (vcpu->arch.debugfs_exit_timing) {
        debugfs_remove(vcpu->arch.debugfs_exit_timing);
        vcpu->arch.debugfs_exit_timing = NULL;
    }
}